1900: A physics genius wandering around Europe

Chapter 670 The End of the Periodic Table! Transuranic Elements! Shocking! Theoretical Contradictions! Uranium and Plutonium!

In the conference room.

Fermi's words piqued the curiosity of all the bigwigs.

The neutron bombardment method and the slow neutron method directly established Fermi's status as a leading figure in experimental physics.

But despite his exceptional talent, he now showed a hint of nervousness.

What kind of experimental phenomenon could move the other party so deeply?

"What Fermi discovered must have gone far beyond neutron bombardment itself."

"Perhaps he collided with and produced a new particle, just like the neutrino predicted by Pauli."

Many bigwigs nodded in agreement, thinking that this was highly likely.

The discovery of a new particle is an absolutely groundbreaking achievement in the field of experimental physics.

Even a top figure like Rutherford would be excited.

Elena's beautiful eyes sparkled. She had just talked to Fermi during her lunch break, and even joked that he could talk about anything he was unsure about.

Surprisingly, Fermi actually had it.

For a moment, Elena was both amused and exasperated.

"Could it be that Fermi was influenced by me to decide to speak?"

"Otherwise, his slow neutron method report would already be amazing enough."

Among the crowd, only Li Qiwei had a deep look in his eyes; he probably knew what Fermi was about to say.

He smiled slightly, as if welcoming the arrival of a certain moment.

"Let's get started~"

While everyone was making their own guesses, Fermi had already composed himself.

After downing a glass of baijiu, his brain was spinning, and he was so high that he lost all sense of time and place.

He opened his mouth and said:
"As I just mentioned, my team bombarded all the elements on the periodic table with neutrons."

"But when bombarding the last element, uranium (element 92), a strange phenomenon was discovered."

"I think we may have created transuranic elements!"

"That is, element number 93."

boom!
As soon as he finished speaking, a tremendous roar erupted in the hall!
Everyone was stunned and speechless!
These bigwigs, like ordinary scholars, lost their composure at this moment.

This news is absolutely explosive.

This is enough to cause a worldwide sensation!

"Oh, God!"

Does transuranic element really exist?

"This is incredible!"

"If Fermi's discovery is true, it will directly rewrite the periodic table!"

As the leading experimentalist present, Rutherford was best able to understand the profound impact of Fermi's concept of transuranium.

He even couldn't help but explain to everyone:

"The transuranic elements following uranium (element 92) have long been an unsolved mystery in the chemical community."

"Many people are searching, but so far, nothing has been found."

"Because according to the rules of electron configuration, the number of electrons in element 93 cannot maintain a stable structure."

"Bohr, you should be very clear about this."

Bohr nodded upon hearing this.

Quantum mechanics is currently widely used in the field of electron configuration.

Chemists have discovered many stable structures, as well as unstable ones.

If element 93 exists, its electron configuration is unstable.

"Therefore, theoretically speaking, it is impossible for it to exist."

"The periodic table can only go up to element number 92."

"This is the special characteristic of uranium."

"In addition, Professor Bruce's proposed nuclear fusion is also a method for producing elements."

"However, it is generally believed that only known elements can be created."

"For example, fusing two hydrogen nuclei into a helium nucleus."

"It is impossible to fuse uranium nuclei into the nuclei of elements 93 or even 94."

Wow!
Rutherford's explanation made everyone realize the truth.

In other words, existing physical and chemical theories do not support the existence of transuranium element 93.

But now, Fermi claims to have discovered element 93, which, as you can imagine, has caused widespread shock.

Rutherford quickly said:
"Fermi, explain your experimental results carefully, without omitting any details."

Everyone could feel Professor Rutherford's excitement.

They were equally excited.

Fermi knew very well that if he spoke, it would cause a terrible sensation.

But now, there's no turning back.

"Everyone, please take a look."

"According to Professor Bohr's droplet model, after bombarding uranium with neutrons, the newly generated nuclides should be near the uranium element."

"However, the chemists on my team did not find any elements below uranium in the reaction products."

"For example, element 91 [protactinium], element 90 [thorium], element 89 [actinium], and element 88 [radium]."

"Therefore, I guess that means that the element generated was one of the 92nd or later, that is, transuranic elements!"

"Whether it is element 93 or element 94 is still uncertain, but I will assume it is element 93 for now."

Wow!
Although Fermi's evidence was not direct, it revealed the essence of element 93.

However, his logical reasoning was flawless.

Since the new element generated after neutron bombardment of uranium is near uranium, once elements below uranium are excluded, what remains must be transuranic elements above uranium.

This logic seems perfectly sound.

In other words, the possibility that Fermi discovered transuranic elements is very high!

For a moment, everyone was breathing heavily.

However, at this moment, Compton asked a strange question.

"Professor Fermi, I have a question."

Fermi said:

"Please speak, Professor Compton."

Compton said:
Why does bombarding uranium with neutrons produce transuranic elements, which are higher than uranium?

"For example, transuranic element number 93 has one more proton than uranium."

"Even if a neutron is captured by a uranium nucleus, it will only result in multiple neutrons, becoming an isotope of uranium. How could it form a transuranic element?"

"In addition, another possibility is that a neutron knocks a small fragment off the nucleus of a uranium atom, creating an element lower than uranium."

"No matter how you look at it, it's impossible for transuranic elements to form, right?"

Compton has been thinking about this problem for a while now, but he just can't figure it out.

However, Fermi smiled slightly.

“Professor Compton, you’ve forgotten an important fact.”

"According to Professor Bruce's theory, neutrons can be transformed into protons."

"When a uranium nucleus captures a neutron, the new nucleus will undergo beta decay, at which point a neutron will be converted into a proton."

"Therefore, element 92 became element 93."

"Uranium was the first naturally radioactive element discovered, and it is very prone to alpha and beta decay."

"Therefore, it is theoretically feasible to produce transuranic elements by bombarding uranium with neutrons."

Wow!
Compton suddenly realized.

"Oh!"

"Yes, there's also the beta decay mechanism!"

"I was so confused."

"Thank you, Professor Fermi. No wonder you were able to discover transuranic elements." Everyone smiled knowingly.

Then, Fermi added:
"The amount of transuranic elements produced by bombarding uranium with neutrons is very small."

Therefore, studying its properties is quite difficult.

"But we still conducted some simple research."

"The properties of the new element are very different from those of protactinium, thorium, and others."

"Therefore, under these conditions, I boldly proposed the hypothesis of transuranic elements."

"However, I did not actually separate and purify transuranium, which is why I was struggling with this before."

"I'm worried this might be a misunderstanding."

"Perhaps there's something wrong with the experiment."

At this moment, everyone finally understood Fermi's performance.

No wonder this young man is so cautious.

He wasn't 100% certain that it was transuranic.

Rutherford said with a smile:

"Fermi, don't worry."

Even if it's a misunderstanding, it's a beautiful misunderstanding.

"Your abilities have already been fully proven."

"No one will think you're trying to show off when it comes to exploring transuranic elements."

The bigwigs all nodded in agreement.

Upon seeing this, Fermi breathed a sigh of relief.

He was afraid that others would think he had abandoned basic scientific ethics in order to be the first to gain honor, and dared to publish results without certainty.

After all, theory and experiment are different.

The former allows for many speculations, but the latter requires data to speak for itself.

At this moment, the bigwigs began a heated discussion.

Fermi has undoubtedly raised a highly controversial question.

According to existing droplet models and theories of electron configuration, transuranium elements cannot exist.

However, according to existing theories such as nuclear fusion and beta decay, transuranium elements can exist.

This creates a contradiction.

Can transuranium elements of type 93 or even 94 actually exist?
Was Fermi's discovery truly about transuranic elements?
No one dares to make a guarantee.

At this moment, even Pauli had to admit that Fermi had indeed brought some remarkable news.

Although it has not been confirmed.

However, after the conference, transuranium will definitely cause endless shock in the scientific community!

Li Qiwei looked at the crowd's discussion and felt a surge of emotion.

What are now common-sense scientific facts that middle school students take for granted were things that took the most brilliant minds of that era more than a decade to figure out.

The progress of science is an epic saga.

Only by truly understanding the story behind each piece of knowledge can one experience the spirit that transcends knowledge itself.

Unfortunately, most people overlook this point.

As of now, the latest periodic table contains 118 elements.

Starting with element 95 [Americium] and ending with element 118 [ào], there are a total of 24 elements, all of which are man-made.

The definition of artificial elements here is very strict.

That is, elements that do not exist in the entire universe and are created artificially.

In astronomy, the elements present in the universe can be determined by measuring the spectrum.

Therefore, although humans cannot truly exhaust the entire universe, a large amount of experimental evidence shows that there is a limit to the types of elements that exist naturally.

The name of the element americium comes from "America".

This element was first artificially created by American nuclear physicist and chemist Seaborg and his team in 1944.

This shows the technological ambitions of the Americans at that time!

Although americium was not the first element to be synthesized artificially, it was the first truly man-made element in nature, which is of great significance.

At this point, some people may have questions.

"Wait a minute, author, didn't you just say that elements 93 and 94 are also transuranic elements, and that they were artificially created?"

"Why do we start with element 95 for man-made elements?"

Is such that.

When Fermi proposed transuranic elements, the only known elements were uranium-92.

Therefore, elements 93 and 94 are considered not to exist naturally and can only be synthesized artificially.

However, with the further development of nuclear physics, physicists discovered that element 93 (neptunium) and element 94 (plutonium) can exist naturally in uranium ore.

The answer lies in the fact that uranium itself undergoes various beta decays, thus having the opportunity to generate small amounts of neptunium and plutonium.

Therefore, neptunium and plutonium were classified as natural elements.

In other words, scientists first artificially synthesized elements 93 and 94, and then found them in nature.

Some articles state that "there are 92 elements in nature," which excludes neptunium and plutonium.

However, nuclear reactions are also a natural part of the universe, so such exclusion is unreasonable.

The generally accepted view is that there are 94 naturally occurring elements in nature and 24 man-made elements.

Plutonium, element number 94, is an extremely important element.

There are two types of fissile materials in the core of an atomic bomb: uranium-235 and plutonium-239.

In 1945, the United States manufactured a total of 3 atomic bombs.

One was used for experiments, and two were used in actual combat.

The atomic bomb used in the experiment used plutonium-239 as its fissile material.

Because uranium-235 was extremely precious at the time.

There are three isotopes of uranium: uranium-234, uranium-235, and uranium-238.

Of the uranium extracted from uranium ore, uranium-235 accounts for a paltry 0.72%, while 99.275% is uranium-238.

Therefore, every gram of uranium-235 is extremely precious.

At that time, someone had already invented a technology to produce plutonium-239 using uranium-238.

Furthermore, plutonium can also undergo nuclear fission.

Therefore, scientists created a plutonium atomic bomb to test the data.

At this point, some people might be curious:

"Since plutonium is so easy to manufacture, why didn't they just manufacture all of it into plutonium atomic bombs?"

This is because plutonium has an extremely high spontaneous fission rate.

To put it bluntly, it's difficult to control; it reacts too easily with neutrons, making it prone to self-destruction.

Imagine how it would feel if you were flying your plane halfway through a flight and the plutonium atomic bomb you were carrying suddenly exploded on its own.

While uranium-235 is extremely rare, it is very stable, as evidenced by controlled nuclear reactors.

Therefore, plutonium can be used to accumulate data for experiments, but uranium must be used for weapon-grade atomic bombs.

Of course, as the technology matured, plutonium atomic bombs became very stable, and its critical mass was only one-third that of uranium, making it very suitable for weapon making.

For example, the famous "Little Boy" contained 64 kg of uranium, but only 1 kg of uranium participated in nuclear fission.

Less than 1 gram of uranium is actually converted into energy.

However, if plutonium is used instead, only 4 kg is needed to achieve the same effect.

However, no matter how good plutonium is, uranium has always occupied the most important position in human nuclear history.

Its fission officially ushered in the far-reaching nuclear energy era.

At this moment, Fermi's proposal of "transuranic elements" was just the beginning.

The story from the discovery of transuranic elements to uranium nuclear fission is also a thrilling one.

This period was filled with various twists and turns and unexpected events, which is truly regrettable.

(End of this chapter)